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Engineering Physics Intern (Fall 2025 / Spring 2026)

2 months ago
Internship
In-person · San Francisco, CA, US... more

About Marathon Fusion

We are building the fuel processing technology to manage and recycle tritium the fuel to unlock clean and abundant fusion energy. Efficient tritium recycling is essential as it minimizes the tritium inventory needed and reduces fuel processing system costs, improving fusion economics and mitigating safety and regulatory challenges around fusion deployment. By working alongside universities, national labs, and industry partners, we aim to ensure the safe and economic deployment of fusion energy at meaningful speed and scale.

Progress and Milestones

We have secured over $10M in funding from a diverse group of mission aligned investors (1517, Strong Atomics, AngloAmerican, and Shared Future), and the US Department of Energy's ARPA-E, with letters of intent from Helion and Commonwealth Fusion Systems—two industry leaders. We also have letters of intent for the plasma centrifuge we are developing, needed today by fission energy companies like Naarea. Our breakthrough achievements include demonstrating a scaling pathway for super-permeable pumps and inventing a novel scheme for differential pumping in the fusion fuel cycle based on the plasma centrifuge concept. (Differential pumping helps separate different types of atoms and molecules, which is vital for fuel recycling).

Marathon Culture

At Marathon, we thrive in a dynamic environment, adapting to rapidly changing circumstances and shifting priorities, all whilst keeping an eye on our long-term goals. This requires excellent communication across roles and backgrounds, a high degree of trust between team members, and the willingness to learn and develop new skills on the job. We place particular weight on a team member's ability to be self-directed and proactive.

Our growing team includes a materials scientist, a computational research engineer, two mechanical engineers and an operations manager working out of our office in San Francisco.

Engineering at Marathon Fusion

The research engineering team is responsible for enabling experimentation, working alongside scientists to understand the objectives and constraints on our devices, and constantly striving to find opportunities to accelerate our R&D roadmap.

During your time, you’ll work to:

  • Conduct hands on design and rapid prototyping

  • Integrate power systems, pneumatics, sensors and mechanical subsystems into our prototypes and test bed

  • Perform mechanical/electrical design in CAD

  • Uphold standards and requirements for ultra-high vacuum environments

  • Procure equipment to meet testing requirements, material standards, and project timelines

Job Requirements

Our work requires a willingness to adapt to rapidly changing circumstances and shifting priorities, while keeping an eye on the long-term goals that ultimately drive success. Navigating this environment necessitates effective communication across roles and backgrounds, a high degree of trust between team members, and the willingness to learn and develop new skills on the job. We place particular weight on a team member's ability to be self-directed and proactive.

Ideal candidates will have experience and interests spanning:

  • Hands on fabrication and rapid prototyping

  • Engineering analysis

  • Excellent written and oral communication skills

  • Progress towards a degree in engineering, physics, or related fields

We are interviewing for interns able to join for at least 10 weeks, any time of year.

We are able to sponsor visas for applicants from outside the U.S.

Marathon Fusion considers all qualified applicants equally for employment. We do not discriminate on the basis of race, color, national origin, ancestry, citizenship status, protected veteran status, religion, physical or mental disability, marital status, sex, sexual orientation, gender identity or expression, age, or any other basis protected by law, ordinance, or regulation.

The salary for this position is $55,000 USD/year, or $26.44/hour. The role is full-time (40 hours a week) and in-person at our San Francisco office.

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